1. Field of the Invention
This invention relates to a return-to-neutral mechanism for a rear wheel steering device. More particularly, it relates to a return-to-neutral mechanism for use in a rear wheel steering device of a vehicle a rear wheel of which is steered under a rotation drive force of an electric motor, such as a four wheel steering system (4WS) of a motor-car, for restoring a rear wheel, once steered, to its neutral position.
2. Related Art
In a vehicle, such as a motor vehicle, in which not only the front wheels but also the rear wheels are steered, there has been known a rear wheel steering device which is adapted to be actuated electro-magnetically by an electric motor or the like.
As the return-to-neutral mechanism for the four wheel steering system, there has so far been disclosed in e.g., JP Patent KOKAI Publication No. 1-161180 (1989) or JP Utility Model KOKAI Publication No. 3-33774 (1991) a return-to-neutral mechanism employing a biasing force of a spring means.
In such prior-art return-to-neutral mechanisms, the rear wheels are steered under the rotational driving force of the electric motor and are restored to or maintained at the neutral position by taking advantage of the force of reaction of a spring which is biased as the rear wheels are steered.